ML17173A551

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Discusses SEP Review of Docket Re Facility Design Bases. Major Review Area Expected to Be Assessment of Significance of Changes in Seismic Design Techniques from Past to Present
ML17173A551
Person / Time
Site: Dresden Constellation icon.png
Issue date: 01/15/1979
From: Stello V
Office of Nuclear Reactor Regulation
To: Reed C
COMMONWEALTH EDISON CO.
References
TASK-03-06, TASK-3-6, TASK-RR NUDOCS 7901250294
Download: ML17173A551 (6)
v • d • e


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  • ~tJTION

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TERA NRC PDR JRBuchanan

  • Local PDR Gray Files*

r 1979

  • j(l.NUAR'f : l il SEPB Reading Xtra Copy {6)

ORB #2 Reading.ACRS 11~6).,

Docket No. 50-23T: *.

Commonweal th Edi son Cooipany ATTN:

Mr~ Cord.ell Reed..

Assistant Vice f~esident Post *Office_ *BOX 7~7..

Chicago, 11 li noi s 60690 DKDavis

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'I HALevin d_,~ -

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RE:

DREsDEN NUCLEAR PmiER STATION UMIT NO. 2 -GB~t:'ber, IE

. DE1 senhut As par*t of the Systematic Evaltiation,Prograni {~\\~ NRC st~ff is conducting a* search of your 'docket for pertinerTt:Rflifonnation related to the ~eismic design bases of your 'facility.

We are comp.aring the available infomat;onwith current seismic design.criteria in an effort tQ*assess safety margins in.the areas of'geologic and seismic i.nput*and *st;ructural Capability of *safety.,..r.elated structures, systems and equipment to with-stand earthquake effects~

As you know, the major NRC regulations dealing with seismic design are

We r~cogniz.e that'both of these reg1;1lations were issued subsequent to the design. of your facility.

However, one of the objectives of the SEP is to compjlre *the original design basis with'c:*urrent criteria~*

Currently, the infonilation on th-e_.. docket is not sufficiently complete to.

adequately address* the potential hazard of earthquakes, nor to determine whether backfitting of additional seismic res*istanc~ woµld pr,ovide sub-stantial ad_dl tion_a1 prot~ction reqµi red for safety.

At this time, based on the docketed information, we expect* that our

  • safety assessment: of *the design bases in your FSAR and other fii i ngs will be positive fn terms of actual safety margins at your facility.
  • However, we encourage you to closely fol low our review as/Jt progresses and *to initiate any *effort that.you may believe necessary to. confirm
  • th~ actual s~i smic safety margJ ns of your facility.

As. part of our assessment, it is expected that we wil;l require significant additional seismic desi-gn ~; nformation *not on the docket to support our sei sm.ic safety assessment~ As our review i ndi c*ates the need for. such i nforma-t-ion, we will inform you.

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...: Commonweal th Edi son... company

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. '.JANUARY 1 b r~!9

  • i4e.expect the major area*_of.rev;ew*.tcrbe our assessment of.the significance of changes.1ri seismic'des*;gn tech'niques from those used for your facility "and those used today.* As'part of the *effort'.to* sat.isfy.~his objective, we*

have. conducted a preliminary '.evaluation Y1tiich indicates that the major area of difference. in' sefsm1c input**'from c*urrent crtter1a rel.ates to the shape of the ground response spec~ra *used. *In this regard, the NRC staff

. is eva*luating various*s1te $pec1f1c.Tesponse spectra methodologi.es which may demonstr'ate a.-more.realist;c approach.fo*determ1ning seismic input

  • .than that used 1 n current.li cen.s i ng
  • reviews~

We encourage you to *closely follow ',the progress of our work.' *Until our. evaluation of site specific re.sponse spectra methodologies*1s.complete,. it is.our intent to*use *..

current criteria design.spectra (e *. g. '*Regulatory Guide 1 ;60, suitably modifie~for inelastic behavio~) ~~*~baseline for our initial'. evaluaticin

  • . o~ _actual *sei sinic safety margins..

. As we. hav~ *di.~cusse!i :With you'. the staf(has. assembled a senior team of

.seismic des 1 gn. experts to evaJ uate the: ac.tu~.1 safety rnargi ns at the Dresden Unit 2 facility. This effort.has.. required significant.interaction *

  • . --.
  • with your technical staff.and your *assistance has been helpful.

We expect

,.

  • that this' effort will Jarge*ly sads'fy the.SEP'.Qbject1ve related to seismic design and any a*ddftiort~l effort will-be* 'detenuine*d as. a result of the conclusio~~ r~*ached.

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  • .-'..':.*Di.vis.ion. of:-.Operating R~actors
  • .** :). 'Office of, Nuc.lear Reactor Regulatto_n

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  • S~E t\\TTACHED YELLO~: FOR PREvrn'us. CONCURRENCE.

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Form AEC-318 (~C'1'. 9-53) AE.CM 0240

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  • u. s. GO_VERNME_NT PPUN!ING 9FF'ICE1 1974.*82~:.uu!

Commonwealth Edison Company cc:

Mr. John W. Rowe Isham, Lincoln & Beale Counselors at Law One First National Plaza, 42nd Floor Chicago, Illinois 60603 Mr. B. B. Stephenson Plant Superintendent Dresden Nuclear Power Station Rural Route #1 Morris, Illinois 60450 Anthony Z. Reisman Natural Resources Defense Council 917 15th Street, N. W.

Washington, D. C.

20005 Morris Public Library 604 Liberty Street Morris, Illinois 60451 U. S. Nuclear Regulatory Commission ATTN:

Jimmy L. Barker Post Office Box 706 Morris, Illinois 60450 Susan N. Sekuler Assistant Attorney General Environmental Control Division 188 W. Randolph Street Suite 2315 Chicago, Illinois 60601

~ANUARY 1 5 ~1§

  • . Commonwea 1th Edi son Company 2 -

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....._/,

We expect the major._ area of review t.o be our asses~ment -of the significance

. cif ~hanges in seistfi.fc *~esign *te~hniques from thos,e used. for your facility and those* used today.* As.part of the effort to satisfy this objective, we have conducted a preJiminary evaluation which indicates' that.the-major area of difference in se1 smic input from current criteria re 1 ~tes to.. the shape of the ground response spectra used.

In th-is regard, the NRC staff.

is evaluating:various site specific response spectra methodologies which may demonstrate *a more realistic approach in determining seismic input. **

than that* u.sed i,n current licensing reviews.

We_ encourage you to closely

- follow the progress:of'our.work. *Until our evaluation of *site specific response spectra methodolQgies is'complete, it is our intent to use current. criteria* design spectra (e.g., Regulatory Guide 1.60, suitably s~itably modi fie~ for inelastic beha~ior) as ~ baseline for our initial evaluation of: actual* sef smi c safety marg1 ns *

. As we*have* dis~ussed with you. the staff has assembled. a senior team of seismic des.igi1 experts to evaluate the actual safety margins at the 1 *

  • Dresden Unit.*2 facility. This effort has required significant interaction..

with' your technical staff and your assistance has been helpful.

~Je expect

  • that thi's effort will largely satisfy the SEP objective related to seismic!,.

, design and any additional effort will _be detennine<i*as a result of *the

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conclusions reached.

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. Sincerely.

)

Victor Stello, Jr., Director Division of Operating Reactors Office of Nuclear Reactor Regulation

  • SE~ ATTACHED YELLOW FOR-PREV16us CON~URRENCE c,,.,.1c11~

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We expec_t-. the ma.jar area of review to *be our assessment of.the significance

"'). o( changes in seismi.c. design techniques* from those used for your facility a_nd those used today., As part of the effort to satisfy thiS objective, we have conducted a preliminary evaluation which* indicates that -the *major area of difference.in seismic input from current criteria relates to the breadth of the ground.response spectra used.

In.:thi s regard. the NRC staff is, evalt.iat;ng v.arfous site specific response spectra methodologies which may demonstrate a more realistic approach in detenni ni ng s~hmic input than that *used. in current 1i cens i ng reviews.

We encourage you to

  • _closely follow the progress of our work ~nd initiate effort in this **area to. better assess the seismic safety margins of your plant.,until *our evaluation of site speci fie response spectra methodologies is complete.

it is our intent to use.current criteria design spectra* (e.g., Regulatory Guide ~.60, suitably modified for ine.lastic behavior) *as a baseline for our initial ev.aluation of actual se~srili't'<sa.fety margins.

\\

As* we.h,~v~ discussed with you~ the staff has assembled _a senior team of

  • seismic design experts to evaluate the actual safety margins at the Dresden Unit~* facility.

This effort:has 'required significant interaction with your-technical staff and your assistance has. been helpful.

\\-le expect that* this. effort wi 11 largely satisfy the SEP objective related to seismic!

design and any additional effort will _be determined as a result of the conclusions. reached.

.\\

cc:

See next page l

. Sincerely,

',Victor Stello, Jr.. Director Division of Operating Reactors Office of Nuclear Reacto~ Regulation

\\'

IOl.C l'OIUI 318 ~9-76) NRCK 02'° R. u.a. oovaRNMll~T PAINTING OP'P'ICI!: t 111

  • aeu -~ 101

January 15, 1979 Note to Howard Levin, EB I looked over the letters re seismic for the SEP plants.

I think they should be sent out as soon as you can.

As I understand it from your people, the letters now reflect the status of this matter as accurately as possible at this stage.

I don't see any specific need for ELD concurrence on these letters.

We do, however, remind you to assure that these letters have ippropriate GAO authorization if such authorization is necessary for the SEP program let_t.ers-.----I beJieve Mr. Felton's office is most cognizant of this./---

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Joseph F. Scinto Deputy Director, Hearing Division lfu-r f-to (\\, I 1:-f'r-rl o 0 51oct OiVL(

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